Reliable potable drinking water sources are scarce in developing countries. High mortality rates can be attributed to inadequate water purification. Cholera, typhoid, dysentery, and rotavirus diarrhea are constant problems faced by people in countries who are forced to use contaminated water.
The lack of safe water supplies perpetuates and aggravates the cycle of poverty and disease. Some efforts have been made to provide clean, potable water in places where power is unavailable. Gravity feed filter systems are normally used to purify non-potable water at the point of use. Gravity feed filter systems are reliable and inexpensive.
The use of halogens such as chlorine, bromine, and iodine for water purification is well documented and widely used in developing countries. The most common forms for treating water with halogens is to add liquid bleach or a chlorine tablet to a pot of non-potable water and to wait for a prescribed period of time before decanting the water. One of the difficulties of using halogens is in maintaining a proper level of residual halogen for proper microbial control. Additionally, iodine, a commonly used halogen in gravity filters, has lost favor with consumers and health officials because iodine causes permanent and debilitating health problems in children and pregnant women.
Recently, polymers having heterocyclic N-halamines have been developed that can provide reliable levels of residual chlorine and bromine. One such agent that holds promise is a halogenated polystyrene hydantoin bead, described in U.S. Pat. No. 6,548,054, to Worley et al., incorporated herein by reference in its entirety.